Merge origin into our fork.

Major accepted PRs on origin:
- Fixed issue where addToken: does not get rid of placeholder text.
- Property added to prevent TITokenField from tokenizing unknown recipients.
- Moved forcePickSearchResult check in resultsForSearchString:
- Converted to ARC

I updated the podspec to reflect that it uses ARC. I've done some brief testing and it looks like everything works okay!